Ferroelectric materials have a dielectric constant which can be altered if a DC-field is induced in the material. This property has been used to manufacture lenses of ferroelectric materials for electrical steering of electromagnetic beams, such as an antenna beam, the beam being the “output” from the lens of an electromagnetic field which has been incident upon the lens.
A lens which is made from a ferroelectric materials and which is used for electrically steering the exit direction of a beam which is incident upon the lens and exits the lens is known from IEEE Transactions on Antennas and Propagation, pp 458-468, volume 47, no 3 1999, “Voltage-Controlled Ferroelectric Lens Phased Arrays”.
A drawback of the device discussed in this article is the complexity of the design and the price. The device uses a multitude of traditional waveguides filled with ferroelectric materials and input/output matching sections which would increase the cost of the device.
Another ferroelectric beam-steering lens is known from 33rd EuMC WS6 proceedings, pp 79-82. Drawbacks of the device disclosed in this paper seem to be a very high charging time constant, as well as quite a high voltage (in the order of magnitude of 20 kV) needed to drive the lens. Additionally, the fabrication of a large area ferroelectric plates (lens) as disclosed in this paper is complicated—it is hard to fabricate the large size (>5×5 cm2) plates of the design with acceptable densification and uniformity.